Figure 1. Dissection of epithelial-cell types in the oesophagus.

The gastro-oesophageal junction between the oesophagus and stomach of mammals is composed of various types of epithelial cell. Jiang et al.¹ describe a transitional epithelial zone between the oesophagus and stomach, and show that the basal and luminal layers of this region, and the epithelia around them, are characterized by differential expression of three marker proteins (KRT5, KRT7 and p63; depicted only on the left-hand side, for simplicity). The authors provide evidence in mice and humans that bile-acid reflux or abnormal gene expression can cause the transitional epithelium to undergo abnormal expansion to form a precancerous tissue containing mucus-secreting goblet cells — a condition called Barrett's oesophagus. (Figure adapted from epithelial graphics in ref. 1.)